With the nation watching, Newtown parents still grieving and gun owners objecting, legislative leaders Monday said they had met the solemn challenge presented by the Sandy Hook school massacre with a bipartisan agreement for the nation's strongest gun control bill.

Easy passage of the legislative response to the Dec. 14 killings is expected in House and Senate votes scheduled for Wednesday, leaders of both the Democratic majority and Republican minority said after completing weeks of negotiations on the bill.

"There were some who said the 'Connecticut effect' would wear off — that it would wear off in Connecticut and it would wear off across the country," Senate President Pro Tempore Donald Williams, D-Brooklyn, said at an evening press conference in the Capitol flanked by five other legislative leaders.

"What they didn't know was that Democrats and Republicans would come together and work to put together the strongest and most comprehensive bill in the United States to fight gun violence, to strengthen the security at our schools, and to provide the mental health services that are necessary," he said.

"Knowing that that tragedy happened in Connecticut, it was up to Connecticut to show the way," said House Minority Leader Larry Cafero, R-Norwalk. "And I'm very proud to say today the package that we are introducing ... has accomplished that goal."

The bipartisan deal would strengthen the state's existing ban on semiautomatic assault rifles to include weapons such as the Bushmaster AR-15 used by Adam Lanza to kill 20 first-graders and six women at Sandy Hook Elementary School in Newtown. Current law defines an assault rifle as having two military-style characteristics on a list of several, such as a pistol grip and a flash suppressor. The new bill would require only one such characteristic. It also lists more than 160 firearms by name as assault weapons.

People could keep the banned rifles that they already own if they submit to new registration procedures. But future sales of the rifles would be prohibited. An existing owner could bequeath an assault rifle to a family member, but could sell it only to a licensed firearms dealer who would have to sell it outside Connecticut.

Magazines Disputed

The bill stepped back from an outright ban on large-capacity magazines containing more than 10 cartridges, such as the 30-round magazines that Lanza used. Instead, it would allow owners of large-capacity magazines to keep them if they make an official declaration by Jan. 1 of how many they own and submit to restrictions on their use. The magazines could only be loaded with 10 or fewer rounds, except in their owners' homes or at a shooting range, where they can be fully loaded.

Buying, selling, importing or transferring high-capacity magazines would be a Class D felony, punishable by up to five years in prison and a $5,000 fine.

Parents of Sandy Hook victims said Monday that they wanted those high-capacity magazines taken away from owners, not "grandfathered in" under the new bill. They called for an up or down vote on that issue.

But Williams and the other leaders who negotiated the agreement said they don't support such a vote because they want to stick to what has been negotiated.

"We learned, the way that no other parents should learn, that the most dangerous, dangerous part of an assault weapon is the magazine," Nicole Hockley, whose son Dylan, 6, was killed Dec. 14, said at a press conference with other parents at the Capitol Monday morning.

"The horrible, brutal truth is that 154 bullets were fired in four minutes, killing our children, our daughters, our wives. The shooter carried 10, 30-round large-capacity magazines," Hockley said. "We have learned that in the time it took him to reload in one of the classrooms, 11 children were able to escape. We ask ourselves every day — every minute — if those magazines had held 10 rounds, forcing the shooter to reload at least six more times, would our children be alive today?"

Lanza killed himself as police arrived at the school. He killed his mother at their Newtown home before driving to the school.

Neil Heslin, whose son, Jesse Lewis, 6, was killed, said Monday night: "I think it's useless to register the magazines. How are you going to register them? I think it's stupid. There's no way to register them, there's no serial numbers. … It's just another law or regulation that's not going to be enforceable." But he said the bill contains other "steps in the right direction."

Democratic Gov. Dannel P. Malloy supported the parents early in the day, saying he agreed with them that "simply banning [the magazines'] sale moving forward would not be an effective solution."

Monday night, when asked if Malloy would sign the negotiated bill into law or if he would veto it, the governor's communications director, Andrew Doba, said he had no additional comment.

Williams said at the press conference that it is leaders' hope and expectation that Malloy will sign the bill.

Meanwhile, the executive director of Connecticut Against Gun Violence, a group that has been allied with many of the Newtown parents and residents of that area, expressed support for the compromise bill.

"We're not totally satisfied with everything," Director Ron Pinciaro said, "but … I think we're in the land of political reality right now … and we're not going to push anybody to push an amendment" for the vote that the Newtown parents requested on the magazine ban. "It's not a perfect day for us but it's a very good day."

The firearms industry expressed dissatisfaction Monday night with the proposal. "It's unfortunate that legislators are moving forward with gun control that's not going to make Connecticut safer," said Jake McGuigan, director of government relations for the Newtown-based National Shooting Sports Foundation.

"I think Cabela's really has to think about whether they can remain in the state as a destination," McGuigan said of the sporting goods megastore in East Hartford. "Based upon this bill, even the ability to sell ammunition is going to be pretty difficult for them. The manufacturers have no reason to stay in Connecticut anymore."

Tighter Rules

Aside from expanding the assault weapons ban and restricting the high-capacity magazines, the bill also would:

•Create what lawmakers believe would be the first statewide dangerous weapon offender registry in the country. People convicted of any of 40 or more specific crimes, most of them involving shootings, would have to put their names on the registry and keep their address current for five years after their release from prison. The registry would be accessible only by law enforcement officials.

•Require a certificate of eligibility or gun permit to be presented by any person buying ammunition. A certificate of eligibility could only be obtained by undergoing a national criminal background check, the same as required for a pistol permit.

•Impose tighter gun-registration procedures and universal background checks for purchasers of all firearms, whether the purchase is from a retail store or between individuals. This would cover purchases at gun shows. Background checks would be required for purchases of long rifles and shotguns.

•Increase penalties for many firearms-trafficking and illegal-possession offenses.

•Increase the "look-back" period for restricting gun possession by persons involuntarily confined or admitted to a hospital for mental illness. Currently, such people cannot possess a firearm or obtain a permit for a year after their release. The bill expands that period to five years.

•Raises the age requirement for purchase of semiautomatic rifles not clarified as assault weapons under the bill to 21, from the current 18.

•Clarify the state's risk reduction credit program, stating that violent criminals who commit crimes with guns must serve at least 85 percent of their prison sentences. Some lawmakers said that this translates into the end of the state's highly controversial early release program, but Malloy administration official Michael P. Lawlor said it is simply a clarification of existing law. Republicans have harshly criticized the early release program, and its inclusion in the gun bill reflects a compromise.